Efficient data acquisition in automated ultrasonic inspection

The large volumes of data resulting from automated ultrasonic inspections illustrate the difficulties of efficient data acquisition and analysis. Consequently, all the available inspection systems impose a compromise between the quantity and the quality of data that they collect and the maximum possible speed of inspection. The paper introduces the problems of ultrasonic data acquisition and assesses several techniques so far employed in inspection systems. A further technique is then described in which only the minimum data required by ultrasonics specialists for defect detection, sizing and characterisation are gathered in a single high-speed scan. This is a technique which is presently being investigated so that the plotting and analysis may be carried out rapidly by discarding data which would otherwise obstruct the interpretation process. The technique requires intelligent discrimination of the features contained in the baseband envelope of the ultrasonic signal. A high-speed signal preprocessor which will implement this technique is under development and is known as the digital ultrasonic signal conditioner (DUSC); its design and applications are described